title: Influence of body mass index on clinicopathological factors including estrogen receptor, progesterone receptor, and Ki67 expression levels in breast cancers.
abstract: BACKGROUND
  High body mass index (BMI) is associated not only with a higher incidence of breast cancers but also with poorer prognosis. It is speculated that both enhanced production of estrogens and other factors associated with obesity are involved in these associations, but the biological characteristics associated with high BMI have yet to be thoroughly identified.
  
  
  METHODS
  We studied 525 breast cancers, focusing on biological differences between tumors associated with high and low BMI and by immunohistochemically defined intrinsic subtype. Ki67 expression levels were used to differentiate luminal A from luminal B estrogen receptor (ER)+/human epidermal growth factor receptor 2 (HER2)-breast cancers.
  
  
  RESULTS
  Premenopausal patients with high BMI showed a significantly higher frequency of lymph node metastasis (46.4 % vs. 22.9 %, P = 0.005) and tended to have a larger tumor size (P = 0.05) and higher nuclear grade (P = 0.07) than those with low BMI. These differences were not observed among postmenopausal patients. BMI was not associated with distribution of breast cancer subtypes, and ER, progesterone receptor (PR), and Ki67 expression levels of each subtype showed no differences between high and low BMI among premenopausal patients.
  
  
  CONCLUSIONS
  Higher BMI might influence aggressive tumor characteristics among premenopausal patients, but its influence on ER, PR, and Ki67 expression levels seems to be limited.
authors.affiliation: Division of Breast and Endocrine, Department of Surgery, Hyogo College of Medicine, Mukogawa-cho 1-1, Nishinomiya, Hyogo, 663-8501, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Yanai
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Miyagawa
authors.forename: Keiko
authors.initials: K
authors.lastname: Murase
authors.forename: Michiko
authors.initials: M
authors.lastname: Imamura
authors.forename: Tomoko
authors.initials: T
authors.lastname: Yagi
authors.forename: Shigetoshi
authors.initials: S
authors.lastname: Ichii
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Takatsuka
authors.forename: Takashi
authors.initials: T
authors.lastname: Ito
authors.forename: Seiichi
authors.initials: S
authors.lastname: Hirota
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Sasa
authors.forename: Toyomasa
authors.initials: T
authors.lastname: Katagiri
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Miyoshi
mesh_terms: D000328:Adult; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism*; D008875:Middle Aged; D017698:Postmenopause; D017697:Premenopause; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism*
chemical_list: D019394:Ki-67 Antigen; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human